The invention relates to steering and tilting means for marine propulsion devices and, more particularly, to gimbal ring arrangements for stern drive or inboard/outboard marine propulsion devices. Hydraulic cylinder/piston assemblies are connected between the ends of the pivot pin and the propulsion unit for effecting pivotal movement of the propulsion unit relative to the gimbal ring.
In prior marine propulsion devices, as is best shown in Prior Art FIGS. 1, 2 and 3, the lower cross-member 1 of the gimbal ring 2 is positioned above the support arms 4, or above a generally horizontal plane including the upper edges of the support arms 4, and a pivot pin 6 extends through aligned apertures in the lower ends of the side members 8 of the gimbal ring 2 and has opposite ends extending outwardly of the side members. The pivot pin 6 is positioned directly forwardly of the support arms 4 and below and cross-member 1. Hydraulic cylinder/piston assemblies are connected between the ends of the pivot pin 6 and the propulsion unit for effecting pivotal movement of the propulsion unit relative to the gimbal ring 2.
In these prior marine propulsion devices, as illustrated in FIG. 3, the result of the propeller thrust forces on the gimbal ring 2 is outward deflection or spreading of the support arms 4. This is caused by bending of the pivot pin 6 which results from the forces applied to the ends of the pivot pin 6 by the cylinder/piston assemblies. Outward deflection of the support arms 4 is undesirable because such deflection reduces the ability of the support arms 4 to absorb lateral forces applied to the propulsion unit.
Attention is directed to the following U.S. patents which disclose gimbal ring type steering means for marine propulsion devices:
Kiekhaefer U.S. Pat. No. 3,136,281, issued June 9, 1964;
Kiekhaefer U.S. Pat. No. 3,136,285, issued June 9, 1964;
North U.S. Pat. No. 3,136,287, issued June 9, 1964;
Kiekhaefer U.S. Pat. No. 3,181,494, issued May 4, 1965;
Alexander U.S. Pat. No. 3,250,501, issued May 10, 1966;
Warburton U.S. Pat. No. 3,403,655, issued Oct. 1, 1968;
Hager U.S. Pat. No. 3,834,345, issued Sept. 10, 1974; and
Weronke U.S. Pat. No. 4,289,488, issued Sept. 15, 1981.